Hair lambs (n 072, crosses of Blackbelly, Dorper, and Katahdin breeds) with an average age of 90 days (21.49 2.3 kg of BW) were used to investigate the effects of sex class (CLASS: ram vs. wether) and zeranol implant (IMP: control vs. 12 mg) on fat and cholesterol content, and fatty acids (FAs) composition of intramuscular longissimus dorsi (LD) and biceps femoris (BF) and subcutaneous fat (SBC) depots of the loin area. Animals were assigned to one of four treatments with a factorial arrangement (n 018): (1) rams (R), (2) rams implanted with 12 mg zeranol (IR), (3) wether lambs (W), and (4) wether lambs implanted with 12 mg zeranol (IW). FAs C12:0 and C15:0 FAs were significantly higher in the wether's LD. The amount of C22:1 n-9 and C24:1 in rams' LD was higher than those of wethers. Wethers had a higher content of C18:1 cis 9 than R group, and the content of this cis isomer was significantly lower in the implanted group. LD of rams contained a higher amount of polyunsaturated fatty acid (PUFA) and a higher PUFA/saturated fatty acid ratio. Cholesterol content in the three tissues (LD, BF, and SBC) was affected significantly by the CLASS)IMP interaction and was higher in wethers without implant. The sex class was the most important factor affecting lipid composition in hair lambs. The higher PUFA content in meat from rams may suggest a nutritional advantage in comparison to meat from wethers.

The results indicate that it is possible to induce favorable changes in the fatty acid profile and cholesterol content using a zeranol implantation strategy on hair lambs.

The meat industry annually produces tons of by-products that represent a cost for the meat processing sector as well as a major environmental problem (Mora et al., 2014; Toldrá et al., 2012). Traditionally, many meat by-products have been used for human consumption. Offal, such as liver, kidneys, and heart are consumed directly after cooking. The heart, which is almost entirely muscle meat and low in fat (Anderson, 2004), is used as a table meat. It can be diced and added to stews or minced and added to other meat for extra flavor